Mixture ratio control for fuel injection pumps



March 26, 1935. K. A. BROWNE MIXTURE RATIO CONTROL FOR FUEL INJECTION PUMPS Fiied Jan. 7, 1932 2 Sheets-Sheet l 1 W 0 m B w N l M L a mm M J. Illiltl E M V I U l m 2 8 J2 4 M w m w p 5:? w a m.

ATTO R N EY March 26, 1935. K. A. BROWNE MIXTURE RATIO CONTROL FOR FUEL INJECTION PUMPS 2 Sheets-Sheet 2 Patented Mar. 26, 1935 UNITED STATES PATENT OFFICE MIXTURE RATIO CONTROL FOR- FUEL INJECTION PUlliPS York Application January 7,

25 Claims.

injection, in particular.

It will be understood that in these injection systms the fuel quantity is controlled by a suitable regulation in the displacement of a pumping or metering device, while the air quantity is usually controlled with a throttle; and mere mechanical linkage for correlating the relative positions of these two controls has been found unsatisfactory because of variations in atmospheric density, and temperature, and because the engine output is not-a constant function of the engine speed under all conditionsof flight.

The following discussion outlines briefly some of the variables which it is the object of this invention to take care of by automatic means so as to maintain the desired air fuel ratio under the widely varying conditions of operation.

The weight of air charge per intake stroke depends primarily upon 1) the density of the surrounding air, (2) the position of the throttle valve, and (3) the speed of the engine. At a constant absolute manifold density the weight of charge does not vary greatly with change in speed within the normal operating range of the engine. At part throttle position, however, the charge varies greatly with speed because of the change in absolute manifold density produced by change in the pressure drop at the throttle. This latter efiect, and the added complication of change in density due to altitude and temperature change, make any positive mechanical linkage between the throttle valve and-the fuel metering control quite unsatisfactory. At full throttle and constant speed the air charge varies as the absolute manifold density and the exhaust back pressure. Reduction in exhaust pressure from altitude causes an increase in air charge at a given absolute manifold pressure over the weight of charge at the same manifold pressure at sea level.

In the drawings:

Fig. 1 is a view, partly in section, through the preferred embodiment of the invention as applied to a distributor type fuel metering device, and

Fig. 2 illustrates the application of a servomotor means to the control mechanism of Fig. 1, which is in this case illustrated with a different or modified form of fuel metering device.

Referring first to Fig. 1, 10 designates a control rod, by axial movement of which the quantity of fuel delivered by a suitable fuel metering 1932, Serial No. 585,236

device 12 is controlled, while 14 designates a fuel pump suited to the particular form of metering device shown. The metering device is more or less conventional and the. present invention is adaptable to any controllable fuel injection means.

At 16 one of the engine intake pipes is indicated. This pipe is provided with an injection jet 18 connected to an appropriate outlet 20 on the metering device 12. It is also provided with an air throttle 22 having suitable connections (not shown) whereby the operator controls the quantity of air admitted to the engine. The appropriate fuel quantity is determined by the position of the control rod 10 which is in turn determined by a cam wedge 24 operated by the automatic control.

Conveniently secured to the back of the injecthe housing 26 by means of an orifice 32. Slidable within the cylinder 30 is a main piston 34 rigidly connected by a rod 36 to an 'auxiliary piston 38 slidingwithin a smaller cylinder 40. The upper sideof this auxiliary piston and cylinder is in communication with the atmosphere through a vent opening 42, while the under side will be seen to be open to the pressure within the easing 26.

A seal comprising a quantity of oil 44 is preferably used above the piston 34 and serves to entrain a predetermined quantity of air in a chamber 46 which is provided with a seated screw 48 by which the initial air quantity may be determined. Preferably the cam wedge 24 is sesured as by means of a laterally floating connection 50 to the piston unit comprising the parts 34, 36 and 38. An adjusting screw 52 backs up against the cam wedge 24, and it is by means of said screw -52 that-the initial position of the cam wedge 24, and therefore of the control rod 10, may be adjusted. It will be seen from the above that the larger piston 34 is subject on its upper side to the elastic pressure from a predetermined quantity of air in the chamber 46; that the upper side of the smaller piston 38 is subject to atmospheric pressure; and that the lower sides of both pistons are subject to the pressure existing in the intake pipe 16 as determined by the opening of the throttle 22 and the atmospheric pressure.

The operation of the device is as follows: Reduction of absolute intake pipe pressure to any given value caused by throttling of valve 22 causes a downward force on pistons 34 and 38 due to the elastic pressure of the volume of air in the chamber 46 above piston 34 and the atmospheric pressure above piston 38 which lowers the piston unit 34-3638 to a position creating an equal and opposite force by the deformation of springs 2'7 and 37. The new position of the cam wedge 24 locates the control rod so as to meter a reduced amount of fuel for the proper engine operation on the reduced intake pressure.

Reduction to the same given absolute intake pipe pressure as assumed above, by an increase of altitude and its accompanying reduction in atmospheric pressure, caused a downward force on the piston 34 due to the elastic pressure ofthe volume of air in the chamber 46, but produces no .force on the piston 38; therefore, the piston unit 34 36-38 will assume a somewhat higher position than that assumed in the case cited above, and consequently cause less reduction of the fuel for the given absolute intake pressure due to altitude than due to throttling by the valve 22.

The quantity of air in the chamber 46 is ordinarily, but not necessarily, that amount present at normal temperature (60 F.) and pressure (29.9 inches, Hg.) when the springs 2'7 and 37 balance each other and there is normal pressure in the casing 26. This quantity (46) is subject to atmospheric temperature and will therefore expand or contract with a rise or fall of temperature from 60 F. Expansion produces downward motion of piston unit 3436-38 to a position creating a force in the springs 2'7 and 3'7 which counteracts the pressure rise from expansion. This downward motion relocates the cam wedge 24 and reduces the amount of fuel metered. The volume of air in relation to the plunger displacement determines the amount of fuel metering changeper degree change in temperature of the air in the chamber 46. Therefore, by using a certain'ratio of areas of piston (34) to piston (38), and a certain ratio of volume in the chamber (46) to the piston (34) displacement, the control position is automatically a function of the weight of air charge entering the cylinder regardless of temperature, and pressure of theatmosphere or throttle position of the engine. The control cam wedge 24 does not have a straight taper but has an outline such as to meter the proper fuel charge for the cylinder air charge density present in the engine. Referring now to Fig. 2, the addition of a servo device is shown. In this figure, 38 again represents the lower piston of the device already described, except that in this case a piston valve 54 is connected to the piston 38, which valve slides in a small cylinder 56. In this case the housing (26') is furnished with a cylinder 58 in which is slidably fitted a piston 60 which carries the valve cylinder 56, the latter being slidably fitted at 62 in the bottom of the housing 26 The piston 60 is provided with a rod 64 having a suitable cam wedge 68 contacting with a roller '10 on a control arm 72 by which the delivery of a suitable fuel metering device 74 is controlled. Fluid under pressure, as from the lubricating pump,of the engine (not shown), is supplied to the pipe '76. A suitable drain pipe '78 is also provided. I

The operation of the servo device is as follows: The oil pressure above the piston 60 depresses this member until the valve 54 reaches the relative position shown whereupon oil is free to escape, as shown by the arrows 80, thus relieving the pressure and preventing further descent of piston 60 and control cam 68. On the other hand, downward movement of the automatic control piston element 38 will lower the valve 54, thus shutting off the escape of oil whereupon the oil pressure will lower the piston 60 and the control cam 68 to correspond to the new position of the valve. It will be seen that a reverse action occurs in the case where the control valve 54 is raised by the pistons of the automatic device of Fig. 1.

By manifold pressure, as used herein, is

ing within the intake manifold, as distinguished meant the pressure in absolute units maintain) from pressures measured in relation to some or, bitrary or variable standard. By atmospheric pressure, as used herein, is meant the absolute pressure of atmosphere in the region of the engine, as distinguished from the absolute pressure maintaining within the intake manifold. By atmospheric temperature", as used herein, is meant the temperature of atmosphere in the region of the engine, as distinguished from the teperature maintained within the intake manifold.

It is to be understood that the above described embodiments of the invention are for the purpose of illustration only, and various changes may be made therein without departing from the spirit and scope of the invention.

What is claimed is:

1. In an .engine, a manually controlled air intake throttle, an injection device controllable for fuel quantity, and an automatic control for said injection device comprising a pair of differential pistons, each subject to manifold vacuum on one side, one subject to atmospheric pressine on the other side, and the other subject to the elastic pressure of a predetermined quantity of elastic fluid.

2. An automatic control for regulating the discharge of a fuel metering device on an engine having an intake throttle comprising, in combination, a pair of pistons subject to manifold pressure on one side, the other sides of said pistons being subject respectively to atmospheric pressure and the elastic pressure from an entrained volumeof elastic fluid.

3. The combination with an engine and fuel injection pump having a fuel quantity control; of

an air intake having a manually adjustable throttie, and an automatic device for actuating said quantity control comprising a main piston having one side responsive to the pressure variations set up in said intake by said throttle, and the other side subject to the pressure from an entrained quantity of elastic fluid, and an auxiliary piston subject to atmospheric pressure.

4. In an engine, in combination, an adjustable delivery fuel pump, a manually controlled air intake throttle, and an automatic means for effecting said adjustment comprising means responsive to the pressure changes set up by the intake throttle, said means being also responsive to variations in atmospheric temperature and pressure. 5. In an engine, an intake manifold, a. fuel injection apparatus having a metering control, and automatic means for actuating said control comprising spring restrained piston means subject to intake manifold pressure, atmospheric pressure and the pressure of a sealed volume of elastic fluid.

. 6. In an engine having a manually controlled air intake throttle and an injection device controllable for fuel quantity; an automatic control for said injection device comprising a pair of differential pistons, each subject to manifold vacuum on one side, one subject to atmospheric pressure on the other side and the other subject to the elastic pressure of a predetermined quantity of elastic fluid, and a spring means elastically opposing the movement of said pistons from a normal position.

7. An automatic control for regulating the discharge of a. fuel metering device on an engine having an intake throttle, comprising a pair of pistons subject to manifold pressure on one side, the other sides of said pistons being subject respectively to atmosphericpressure and to the elastic pressure from an entrained volume of elastic fluid, and a spring means elastically opposing the movement of said pistons from a normal position.

8. The combinationwith an engine and fuel injection pump having a fuel quantity control; of an air intake having a manually adjustable throttle and an automatic device for actuating said quantity control comprising a main piston having one side responsive to the pressure variations set up in said intake by said throttle, and the other side-subject to the pressure from an entrained quantity of elastic fluid, an auxiliary piston subject to atmospheric pressure, and a spring means elastically opposing the movement of said piston from a normal position.

9. In an engine having an adjustable delivery fuel pump and a manually controlled air intake throttle, an automatic means for effecting said control comprising a piston means responsive to the pressure changes set up by the intake throttle, said piston means being also responsive to variations in atmospheric temperature and pressure, and a spring means elastically opposing the movement of said piston from a normal position.

10. In an engine, in combination; an intake manifold; a fuel metering device; and an automatic means for controlling said metering device comprising a resilient member adapted to normally adjust said metering device to a predeter mined amount of fuel flow, and means adapted to deflect said resilient member, responsive in its operation to changes in atmospheric pressure, in atmospheric temperature, and in manifold pressure.

11. In an engine, an intake manifold, a fuel metering device, a housing, a member movable,

within said housing and adapted to define therein a plurality of compartments, said member being adapted to control said metering device, one said compartment being sealed to entrain a fixed content of elastic fluid and the other said compartments each communicating respectively with the outside air and with the intake manifold.

12. In an engine, an intake manifold, a fuel metering device including a housing, a member movable with respect to said housing, said member and said housing defining a space adapted to contain a fixed weight of elastic fluid, said member being responsive in its movement to changes in volume of said elastic fluid, and partitions within said housing coacting with said member to define additional spaces, each said space being in communication with the intake manifold and with the atmosphere, respectively.

13. In an engine, in combination, an intake manifold, a manually controlled throttle in said manifold, a fuel pump, a fuel metering device in communication with said pump, a fuel jet in communication with said device for directing fuel into said engine, and automatic means for operating said metering device responsive in its operation to changes in manifold pressure, in atmospheric pressure, and in atmosperic temperature.

14. In an engine, in combination, an air intake manifold, a throttle valve in said manifold, a fuel injection jet in said manifold between said throt tle and the engine, a fuel injection pump for supplying fuel to said jet, and means for controlling the amount of fuel supplied to said jet automatically dependent on the pressure in the region of said jet, on atmospheric temperature and on atmospheric pressure.

15. In an engine, in combination, an intake manifold, a manually controlled throttle in said manifold, a fuel pump, a fuel metering device in communication with said pump, a fuel jet in communication with said device for injecting fuel directly into a portion of said engine, and automatic means for operating said metering device responsive in its operation to atmospheric pressure.

16. In an engine, in combination, an intake manifold, a manually controlled throttle in said manifold, a fuel pump, a fuel metering device in communication with said pump, a fuel jet in communication with said devicefor injecting fuel- 17. In combination, in an engine, an air intake manifold, manually operable means for controlling the amount of air passing through said manifold and into said engine, means driven by said engine for intermittently supplying metered quantities of liquid fuel to said engine, and a device acting on said engine driven means for changing the metered quantities of fuel delivered thereby, said device being automatically responsive in its operation to changes in atmospheric pressure.

18. In combination, in an engine, an air intake manifold, manually operable means for controlling the amount of air passing through said manifold and into said engine, means driven by said engine for intermittently supplying metered quantities of liquid fuel to said engine, and a device acting on said engine driven means for changing the metered quantities of fuel delivered thereby, said device being automatically responsive in its operation to changes in atmospheric temperature.

19. In an engine fuel injection system, a movable member for varying the amount of fuel injected, a cam engageable with said member'and movable both in a plane substantially normal to the plane of movement of said member and in the plane of movement of said member, means for moving said cam in one said plane responsive in its action tochanges in engine operating characteristics, and adjustable means for moving said rectly into a portion of said engine, and automatic means organized to vary the amount of fuel passing through said device, responsive in its operation to changes in atmospheric temperaure.

21. In an engine having an air intake manifold, a manually controlled throttle in said manifold, and means for intermittently injecting metered quantities of liquid fuel to a portion of said engine; a device for changing the metered quantities of fuel comprising a housing, movable means within said housing defining compartments therein, a connection from said manifold to one said compartment by which the reduction in manifold pressure moves said movable means to reduce the quantity of metered fuel, and a connection between another said compartment and the atmosphere by which a reduction in atmospheric pressure moves said manifold means to increase the quantity of metered fuel.

22. In an engine having an intake manifold, a manually controlledthrottle in said manifold, and means for intermittently injecting metered quantities of liquid fuel to a portion of said engine; a device for changing the metered fuel quantities comprising a housing, relatively small movable means in said housing defining therewith a compartment, said compartment being in communication with the atmosphere, relatively large movable means in said housing, movable with said relatively small means, and defining with said housing a second compartment, and a connection. from said second compartment to said intake manifold.

23. In an engine having an intake manifold, a manually controlled throttle in said manifold, and means'for intermittently injecting and metering quantities of liquid fuel to a portion of said engine; a device acting on said metering means for changing the quantities of fuel delivered thereby, and means for operating said device comprising two compartments, one said compartment being in communication with the intake manifold and the other said compartment being in communication with the outside atmosphere, movable means in each said compartment responsivein its movement to the pressure existing therein, and means linking each said movable means with said device by which a specific change in pressure in said atmospheric responsive compartment effects a specific movement of said device, and by which the same degree of pressure change in said manifold connected compartment effects a greater degree of movement of said device.

24. A fuel air ratio control for an engine fuel injection system including a manually throttled air manifold and means for intermittently metering and injecting quantities of liquid fuel to said engine comprising a device for biasing said metering means for changing the quantities of fuel metered, means responsive to atmospheric pressure acting on said device for effecting a finite change thereof in response to a finite change in atmospheric pressure, and manifold pressure responsive means acting on said device for efiecting a change greater than said first finite change in response to a manifold pressure change substantially equal in degree to said atmospheric pressure change.

25. A fuel air ratio control for an engine fuel injection system including a manually throttled air manifold and means for intermittently metering and injecting quantities of liquid fuel to said engine comprising means for changing the quantities of fuel metered, and means responsive on the one hand to changes in atmospheric pressure and responsive on the other hand to changes in manifold pressure for acting on said changing means, said responsive means being differentially effective in acting on said changing means under the influence of substantially equal changes in atmospheric pressure and in manifold pressure.

KE'NNE'IH A. BROWNE. 

